Proposed here are several epidemiologic and laboratory studies designed to: ascertain the prevalence and spectrum of clinically palpable benign breast disease across racial groups whose breast cancer rates are known to vary; examine the association of known or suspected breast cancer risk factors and clinical benign breast disease, by race; determine the pathologic spectrum of breast tissue from biopsy series, by race, and the epidemiologic characteristics associated with different pathologic diagnoses; and investigate cytologic measures which might serve to differentiate women with healthy breasts and those with benign and malignant breast disease, by race.